Pencil sharpener



1931- E. WILDHABER ET AL 1,790,255

PENC IL SHARPENER Filed July 10, 1928 2 Sheets-Sheet I INVENTORS Jan. 27, 1931. 'E. WILDHABER ET AL 1,790,255

PENCIL SHARPENER Filed July 10, 1928 2 Sheets-Sheet 2 INVENTOR M6: WJAM.

entrain] m Patented Jan. 27, 1931 res EPATENT OFF C giinnnsn-wrrnnnnnn, or BRooKLYn, AND :rosnrn esryn', omocnasmn, NEW YORK j I PEnoIr. SHARPENER Application. filed July 10, 1928.) Serial No; 291.669.

Our invention relates to pencil sharpeners,.

' V, and particularly to such pencil Sharpeners in which rotary cutters are used to obtain a 'desired pencil .pointi Penc l sharpeners of known 'constructlons furnish conical or Substantially conical pencil endsyin which the lead terminates in a point.

A sharp point of a'pencil is known to wear off quickly in use and pencils so sharpened thereforeneedfrequent repoi'nting,at leastwhen they are to be used for drawing accurate "or I fine lines; Moreover a sharp pencil point may room ractice to re 'rind a encil b hand break off easily.

Forthese reasons it"isl conimon drawing noti Single. P but rather to an edg as will be further. described hereafter; pencil pre'servesa keen edge much longer than it can preserve a-single sharp point, and there fore continues much longer to give fine and sharpener suited to furnish a pencil point of greatstrength. A. further and lmportant aim is to provide a pencil sharpener sulted to furnish an oval pencil point which is reinforced by projections'of the wooden case of the pencll.

A still other aim is to provide a pencil sharpener of very simple and rigid construetion which is suited to give the novel per-- v formance described.

i ,of the specification and from recital of the. p a a Another object is to devise a pencil sharpener having special provision for preventlng the pencil point from breaking 1n the sharpening operation, and which furnishes a very smooth'cut.

Further objects will appear, in the course appended claims.

Embodiments of our lnvention Fig. 1 is a sectional view of one embodiinventionare illus-l trated in the accompanying draw ngs, n .which merit of a pencil sharpener constructed in beingtaken along lines 1 l of Fig. 2.

Fig. 2 is a front elevational View icorr'esponding to Fig.1. 7 p Fig; 3 is an endview of the pencil sharpener shownin Fig; 1,' the view being talrenloolc ing at side- Fig. 4 and Fig. 5 are diagrammatic .views of two different'position's of an 'eccentr'ically mounted cutter in engagement-with a pencil end illustrative of Fig. 6 and Fig. '7 are diagrammatic views so a principle of-thepresent of a cutter engaging a pencil-end, the axis of rotation of said cutter being inclined to the center line of the cutter body. f Fig. 8 and Fig. 9 vare diagrammatic views of the. disposition shown-in the 'Figuresl t03. i I i cutter.

Of a cutter engaginga pencil end,' illustrative Fig. .10 is an end view of an individual Fig.. 11 is a diagrammatic View of an-.

other enibodiinentof the presentinvention.

Fig. 12 is a side view corresponding to Fig. 11 of t-hepencil end and of thecutter,

theview being taken at right'angles'tothe 7 plane cutting surface.

Fig. 1 3 is a gear diagram illustrative of a 'way ofgearing up two cutters at the ratio of onelto two with respect to' a member concentric with the pencil, while avoiding interference between the two pinions forming part of the cutters.

14 is a gear diagram similarto Fig. l3 and illustrative of the disposition used in the Figures 1 to 3.

-Referring to the Figures 1 to 3, the nun eral 11: denotes a casing having a socket lEZ, which may befas tened to any'suitable support, such as a table, by' means of screwsdisposed in the holes 18. Casing 11' contains a bearing 14 rotatably'holding an extension 15 of a planet carrier 16. The latter may be turned on its-axis by me'ansof afcrank 17 having a'handle. 17 I Planet 'carrier 16 contains two-planets 18,

present instance are angularly v disposed to the axis (l5) of the planet carrier 16 and 19, rotatable on axes 20, 21, which in the j offset from said axis. The planets 18, 19 are in the form of milling cutters and contain pinions 22, 23 rigidly connected with them, which mesh with an internal gear 24 secured to casing 11. As the crank 17 is turned, the planets 18, 19 move bodily about axis and, owing to the mesh between .the planetary pinions 22, 23 and the stationary internal gear 24:, turn on pins 20, 21, which are screwed to the planetcarrier 16- withetheir ends 25. Y

The pencils to be sharpened are introduced through opening 26 coaxial with axis 15 and advanced into engagement with the milling cutters 18, 19, and are prevented by hand from turning; The said milling c tters then form the end of" the pencil in their planetary motions. A

We will now proceed to particularly describe the novel principles and features characterizin the present invention.

Accorc ing to our invention the centers of the cutter surfaces (18, 19) differ from the centers 20, 21 oi rotation. An object herewith attained will first be described with reference to Fig. 4 and Fig. 5.

In these' figures, the axis of rotation is shown ottset from the center of the surface of the cutter body 18, and parallel to said center. The surface of-cutter body 18 is a cylindrical surface in the instance illustrated. The axis of rotation intersects the axis15. of pencil 31 in a point 32, which maintains its position during the planetary motion/of the cutter about axis 15, In Fig. 1 the position of the cutter- 18 is illustrated in which the axis of rotation 20 is inside of the center 30 of the cutter's'uria'ce, where the centers 20, 30 and 15 are all lying in the same plane. Fig. 5 illustrates a position, in which the cutter 18 has been turned'by half a revolution as compared with the position shown in Fig. 4, and where the axis oi? rotation 20 is outside of the center 80, the centers 20, 30 and .15 again lying all in the "same plane.

In accordance with our invention, the ratio between the rotation of the cutter 18 on its axis 20 and the planetary rotation of the cutter body on axis 15 is two to one. This corresponds to a number of teeth on internal gear 24 twice as large as the; number of teeth of the pinions 22, 23 inthe embodiment of our inventionillustrated in Fig. l't'o Fig. 3. With 7 the said ratio of two to one, the cutter'surface approaches the center of the eneilsi (Fig. 4 and Fig. '5) to a minimum distance twice per planetary revolution on center 15;

and it draws way from the pencilceiiter to a maximum distance also twice per revolution on center 15. The position corresponding to a maximum distance between the cutter surface 18 and the axis 15 of tli'e pencil :is illustrated in Fig. 1 tandFig. 5 'sho'ws'the psi'tiei oi minimum distance. The end 33' of pencil 31 is formulae :1 surface enveloped by the various relative positions of the out ter surface (18) and is found to be of oval remote from'the center of the pencil, see Fig.

fl.-- Figsd moreover accords a view of the broad side of the pencilend, and Fig. 51111"- 11131183 a view of the narrow side of-the pencil en It is particularlynoted that the pencil lead 34 resulting iroman eccentriccutter 18 terminates in an edge 34-, that isto say in a roundedline, and moreover, that the woodenpencil case 35 reinforcesthe lead with two extensions-36 adjacent the narrow sides of the pencil end,.see Fig. 4. These extensions 36 are naturally and automatically formed in the sharpening operation without further provision.

-Fig. Band Fig. 7 illustrate a slightly modifled disposition of the axis-oi rotation 20 relatively to thecenter 30 of the cutter surface. The twoc'enter's 20 and 30 are angularly disposed to each other, and intersect in a point 38 on theside otthe cutter which forms the portion where the pencil end meetsthe outside surface of the pencil. Thecutter surf-ace contains therefore an eccentricity changing lengthwise ofthe cutter. The said eccentricity isinaximum adjacent the lead 84 of the pencil, and it is reduced to zero adj acent the above said position, which is formed truly circular. The form of the lead end 34: itself obtained from the disposition illustrated in Fig. 6 and Fig.7 is substantially the same as in the disposition shown in Fig. 4 and Fig.

5, when the eccentricities of the cutter surfaces are the same adjacent said lead end.

The term lead is used in the present specification with-th'e broad meaning of pencil filling, which may be of anysuitable material,

especially also graphite mixtures.

Fig. 8 and Fig. 9 illustrate the general disposition of cutter center 30 and axis of rotation 20 as used in the embodiment of our invention illustrated in the Figures 1 to 3. Along the whole length of the cutter, its

center 30 is oifset from the axis of rotation 20, and the amount of offset increases towards the side adjacent portion 10', where the pencil end meets the outside surface of the pencil. The center lines 30 and 20 may be disposed to. either intersect in a point outside of the cutter body, or, if so desired, they may be disposed askew, so that they do not intersect at all. j 7

Fig. 8 is a view looking at the broad side of pencil 31, with the surface of cutter 18 at a maximum distance from the center of the pencil. Fig. 9 is a view looking at the narrow side of pencil 31, with the cutter su'r- 'iso face in min'imum'distance froin the pencil gcentenp' The disposition indicated. in Fig. 8

. and Fig. 9ipermits to obtain extensions 36 of 1 increased strength. For convenience the cutter surface 18 and axis of rotation 20 are shown as if said axis would intersect the axis 15' of planetary motion, whereas in the embodiment shownin Fig. 1.to Fig. 3, to

which F d g- 9 correspond, the axes "20 are slightly ofi'set from axisl5.

Cutter 18 is preferably made inthe form ofa milling cutter having cutting edges dis posed in a surface of revolutlon, such as a, cylindrical surface in the nstance lllustrated the direction of its axis.

The said gripping means consist of a elastic steel rlng 44 containing two pro ections 45 forming jaws 46. The said projections 45 as well as further projections 47 disposed at right anglesthereto are guided inradial slots of a ring 48 secured to casing 11. .Under the influence of the spring means constituted by steel ring 44, the jaws 46 tend to approach each other'and to securely grip a pencil introduced 7 through opening 26.

. 51 concentric with Prior to introducinga pencil, ring 44 is pressed together by hand in a manner that the projections 47 are radially approached to each other in the directions of arrows 49.

As the curve of the ring 44 gets flatter adjacent saidprojections, the other projections 45 .1 v In the embodiment of our invention diagrammatically illustrated in Fig. 11 and Fig. 12, the active surface of cutter 18 is a plane disposed at an acute angle 50 to its axis of rotation 20. A view at right angles to said plane is illustrated in Fig. 12. Cutter 18 is geared up with a stationary tapered sun gear pencil 31 by means of a hypoid pinion 52.

Theratio between gear 51 and pinion 52 is again two to one, as in the embodiments already referred to. This ratio of two to one is chosen to obtainthe desired oval form of the pencil end. The cutter 18 is made to could be substituted by rotation on two fixed .20, 21 parallel to axis 15'.

centers, if so'desired, namely on the axis 20 of the cutter 18 and-ona center 15 coaxial withfthe pencil, asis readily understood by those skilled in the mechanical art.

Milling'cutter 18 is preferably provided with curved or spiral flutes 53"forming cutting edges 54which are substantially perpen-' dicular to-the line of contact 55 between the pencil and the cutting plane of mill-ing cutter 18, see Fig, 12. i The curves 54may for instance be made involutes, having-a base circle'56. The cutter is rotatedin the-direcs t-ionof arrow 57 ,so-that the cutting edges 54 'act'ba-ckwardly from the lead edg'e'towards the main body of the pencil, while remain ing substantially perpendicular to thegeneratrices. of the: oval pencil ends The cutting pressure is .then always directed: backwardly "in a direction to effect a' minimum bending moment on "the pencil, so that thereis no danger" at all'to-bre'ak'oii the' lead of the pencil; Also when the cutting --edges 1 (54) of the millingcutter l8" aremade straight, they are preferably disposed at such inclination relatively to radial lines, that they are, perpendicular to theline of contact55 at least adjacent the lead-end 34.

When a single milling cutter 18 'isu'sed, or when itsaxis 20 of rotation is disposed ata large angle-(50) to the axis (15") of plane tary rotation, as in the embodimentdiagrammatically illustrated in Fig. 11 andiFigg-ls,

no difiiculty-is experienced ofobtaining a ratio of two to-onewith known means,

When however twocuttersare used having axes 20, 21-parallel to the axis 15" of. the planetary motion,or having aXes'QO, 21 inclined by small angles relatively to axis-15, as in theembodiment illustrated inthe Fig ures 1 to 8,'the'n it is found somewhat difficult to. prevent the two pinions (22, 23) connected with the two. cutters from interfer-, ing with each other, when employing conventional gear design. This difficulty is illustrated in Fig. {13 for cutters having axes At a two'to one ratio 'thepitch circles. 58. of the pinions are half the size'of the pitch circle 60 of internal gear '24, and they contact with each other at center 15. In conventional practice gear teeth are proportioned so that the active tooth surfacesex tend equal amounts above and below the pitch circles, (.58, 6 0). In other known cases the pinion is provided with teeth extendingby a larger amount outside of the-pitch circle than inside of the pitch circle, The pinion contains then what is commonly called increased addenda, while the mating gear contains redu'cedaddenda. I In the present case we provide teeth, 61 on the'pinions extending wholly inside of the pitch circles 58, that 1s to sayteeth '61 which consist solely of dedenda, so that the outside diameter of the pinions is slightly smaller lie than their pitch diameter. Moreover We increase the pressure angle 62 or inclination angle 62 of the-line of action above thestandard amount, and thereby obtain a satisfae' tory duration of action alsowhenthe tooth number of the .pinions is small. I

p The aspect of the gear problem does not change -materially, when the axes 2'0, '21- of rotation of the pinions 1 8, 19 are somewhat tilted with respect to central axis 15, see Fig. 14. This disposition corresponds to the embodiment shown in theFigures 1 to 3. The pinions are provided with increased dedenda, so that they do not interfere with each other adjacent axis 15, and are further provided with increased pressure angles; Preferably the teeth -61 of the pinions are made straight and parallel to their axes of rotation, whereas the teeth 63 of internal gear '64 (Fig. 14.) are made slightly helical.

In either case (Fig. 18 and Fig. let) the outside diameter of the pinions is less than one half of the root diameter of the internal gear.

Pencils provided with an oval end, put within 'easy reach through our novel pencil sharpener, are not confined to use in draw- 7 ing rooms, but may be generally used. They are convenientfor writing as well as for sketchin They give shades or heavy lines without effort, andthey are stronger and longer wearing'than pencils sharpened to a single point.

Numerous modifications may be made in our invention without departing from its spirit, by simply applying the general knowledgeof theart. For definition of the scope of our invention we relyon the appended claims.

WVhat we claim is:

1. A pencil sharpener, containing a plurality of cutting edges, means for moving said cutting edges relatively to a pencil in paths differently located relatively to the axis of said pencil, and means for effecting different 3. A pencil sharpenenrontaining cutting member provided with a plurality of cutting edges means for rotating said member, means for providing turning motion between said member and a pencil on an axis coinciding with the center line of said pencil to efiect contact between the pencil and the surface of said cutting member along a line moving around the center line of said pencil,

and means for displacing said line relatively to the center line 0 the pencil.

4. Apencil sharpener, containing a milling cutter provided with cutting edges disposed in a surface of revolut1on,jthe center line of said surface being oifset 'fromthe axis of rotation of said cutter, means for rotating said cutter on said axis, and means for effecting turning motion between said cutter. and a pencil on an axis coinciding with the centerline of said pencil,sa-id turning motion being timed up with the rotation of the cutter on its axis. i V

5. Apencil sharpener, containing a pair of milling cutters provided with cutting edges disposed in sunfaces of revolution of straight profilein axial section, the center lines of'sai-d surfaces beingoffset from the axes of rotation of said cutters, means for centering a pencil, means for rotating said cutters on their respective axes, and ,means for bodily moving said cutters na planetary pathabout an axis coinciding with-the center line of said pencil in timed relation to the rotation of said cutters on their axes.

6 A pencil sharpener, containing a pair of millin cutters provided: with cuttingedges lines of said surfaces difi'ering fromthe axes of rotation of said'cutters, means for-rotating said cutters ontheir'respecti ve axes, means for bodily moving said cutters in a planetary path aboutan axis coincidingwith the center line of a pencil introduced for sharpening,

and means for timingup the rotation of said cutters and their planetary motion at a ratio of two to one, so that-the cutters turntwice on their'axes'per planetary revolution."

7. A pencil sharpener, containing a milling cutter having a centerilinedifiering from its an axis coinciding with the center line of a pencil, and gears operatively connecting said cutter with a stationary casing at a ratio of one to two, the gear connected with said casing having twice the number of teeth of the gear connected with said cutter.

K9. A pencil sharpener for producing an oval pencil end, consisting of a rotary cutter, means for rotating said cutter, and means for effecting turning motion between said cutter and apencil at a ratio of one revolution per two revolutions of the cutter on its axis.

10. In a pencil sharpener, a cutter having cutting edges formed by flutes, the flutes being disposed'a't such inclination'on the surr V disposed in cylindrical surfaces, the center face of said cutter, that they are substantially perpendicular to theline of contact between the surface of the cutter and the end of a pencil adjacent its lead.

11. A pencil sharpener for producing an oval pencil end, comprlsing cutting 11163118,

- means for centering a pericihmeans for mov'- ing said cutting means and. said pencil relatively to each other in a manner to cover the connected with said cutters fortimingup entire periphery of the pencil with said.cut ting means, and means forefiecting, anloval pencil end.

12. In a pencil sharpener forproducing an oval pencil end, a pair of milling cutters, V means for effectingturn'ing motion between said cutters and a pencil, an internal gear meshing at a ratio of two to one withpinions I said turning motion with the rotation of the I cutters on their axes, the outside diameter of the pinions being less than one half of the root diameter of the internal gear. 3

13. In a pencil sharpener for producing an oval pencil end, a pair of milling cutters, means for bodily moving said cutters around a pencil, an internal gear meshing at a ratio of two to one with pinions-connected with said cutters for timing up said motion with v the rotation ofthe cutters on theiraxes, the outside diameter of the pinions being. less. than one half of the root diameter of the in-.

ternal gear.

14. A pencil sharpener, containing a rotary 7 cutter provided with a plurality of cutting edges, means for moving said cutting edges relatively to apencil in paths differently located relatively to the center line of said pencil, means for effecting turning motion between said cutter and said pencil about an axis coinciding with the centerline of saidf pencil, and timlngmeans for movlng said cut-.

edges, means for moving said cutting edgesrelatively to a pencil in paths differently located relatively to the center line of said I 7 pencil, means for maintaining said pencil centeredwlth spring pressure, means foreffecting turning motion between said cutter and said pencil, and timing means for efiectg ing engagement between said cutting edges andsaid pencil exactlytwice per revolution of said turning motion.

I 1- 18. A pencil sharpener, containing a rotary cutter provided with a plurality of cutting edges, said cutting edges having difierent distances from the axis of rotation of'said cutter, means forrotating said cutter on its axis, i

and means for moving said axis about the center line of a pencil, in timed relation to the rotation of said cutter on its axis.

ERNEST WILDHABER. V Josnrnes'rra ting edges into engagement withsaid pencil Q exactly twice per revolution about saidaxls.

15. A'pencil sharpener, containing a milling cutter provided with cutting edges disposed in a surface of revolution, said cutter being rotatably mounted on an axis extending inside of said surface and angularly disposed to the'center line of said surface, means for rotating said cutter on its axis, and means for effecting turning motion between said outter and a pencil in'timed relation to therota I 7 tion of said cutter. v i 16. A pencil sharpener, containing a pair -of cylindrical milling cutters rotatably mounted on axes extending inside of the cylindrical cutting surfaces of said milling cutterspsaid axes being angularly disposed to the center lines of said'cylindrical cutting surfaces, means 'for rotating said cutters on saidaxes, and means for bodily moving isaid cutters about a pencil'in timed relation to the i V r rotation of said cutters.

l7. A'pencil sharpenenrcontainingarotary Y cutterprovided with a plurality of cutting 

